Is it good to seal threadings in hydraulic systems with fluoroplastic tape?

No, it doesn't dissolve. The problem is that threads tend to cut off small pieces which can wreak havoc with things like valves. And, of course, if the threads cut it, it can then leak (I know, all hydraulic systems leak but it is a matter of how much).

I have used it for hydraulics when nothing else was available. I used a single layer and kept the edge back from the end of the male thread. And, I promised myself I would never disassemble that joint.

Hello TVP45,

Very good answer!

I know others have said the same thing and the same reply is sent to them through the ether!

stay safe

babybear

The only caution that I have heard in not using a teflon sealants tapes is that stray pieces on the fittings may come loose. They may get ground up by the pump and can plug small ports. I was taught to use a paste unless I was sure there were no small ports in the system.

I despise the stuff, & will never willingly use it!

Welcome aboard! We seem to have consensus here - NO - don't use it! Actually, it's OK for water pipe fittings, but I wouldn't use it for anything else.

Loctite makes a really handy stick of pipe thread paste. Just put it around the threads like lipstick and thread the ends together. It's much easier to use than tape, and no loose strings. No, I don't actually use lipstick myself, but I watch my wife use it. (On a different note, I do actually keep lipstick in my toolbox. It's great to put onto one of two mating surfaces to press them together and find the high spots. Don't use your wife's good lipstick, though. I use a color that she bought, but just "didn't look good on." The pieces of metal or wood don't seem to care about the color.)

"...find the high spots..."

Presumably, a real floozy-red color might find the low spots instead, though, huh? That's a neat tip!

What kind fittings do you have? What kind of hydraulic oil is it: MIL-H-5606, MIL-H-83282, or MIL-H-81019,

I have seen tape used on systems with 5606 but none of the others.

I have never nor would ever use it. If you are using AN (JIC) fittings they make aluminum sealing washers for the flares that are certified for use on aircraft.

FWIW, I was told in a training class put on by Aeroquip that contrary to popular belief, TEFLON TAPE was not designed as a SEALANT. It is actually a LUBRICANT that allows NPT Pipe Threads to be turned easier as the Taper forces greater Metal to Metal contact. Sounded logical to me after seeing the amount of Leakage on threads using the stuff.

No OIL HYDRAULIC Circuit should be plumbed with NPT Pipe Threads if there is SHOCK in the system or if the pressure is above 250 PSI.

Always use Straight Thread "O" Ring Fittings and Tube or 4-Bolt Flange Fittings with Welded Tube or Pipe.

Design the circuit free of shock and there will be no leaks when everything is installed per the manufacturer of the fittings recommendation.

The latest and best I've seen is by a company called Tube-Mac and appears to be Bullet Proof after 4 years on a line that covered a half acre and had over 250 Actuators and Valves. The Tube-mac www.tube-mac.com piping was used on the miles of plumbing that fed the valve stands and everything else was Straight Thread "O" Ring fittings.

I'm sure the instllation was not cheap, handled by a crew of about 30 from Tube-mac employees on site for a month, but the results are well worth it.

BTW i have no affiliation with Tube-mac.